Track-type machines, for example excavators, dozers, and skid-steer loaders typically include a frame that supports an internal combustion engine, and left and right undercarriages that transfer power from the engine to a ground surface. Each of the undercarriages includes one or more sprockets, driven by the engine, at one end and an idler wheel located at an opposite end. A plurality of roller assemblies support an endless track wrapped in a loop around the sprocket and idler.
Over time, wear in the roller assemblies can introduce slack in the tracks, which in turn can cause the tracks to wear excessively, break, and/or to slip off the drive sprocket and idler wheel(s). To minimize the occurrence of slack, the worn out roller assemblies must be repaired or replaced. Frequent repair or replacement of the roller assemblies can, however, increase the cost of operating the track-type machine because of the added cost of replacement parts and because the repair and replacement of the roller assemblies require the machine to be placed out of service. Accordingly, increasing the operating life and reducing replacement cost of the roller assemblies become important factors in reducing the operating expenses associated with a track-type machine.
U.S. Pat. No. 6,481,807 of Barani et al. issued on Nov. 19, 2002 (“the '807 patent”) discloses a sliding roller for the tracks of tracked vehicles. In particular, the '807 patent discloses a roller having a stepped shaft with a central collar and shanks at each end of the shaft. The shanks have a smaller diameter compared to the shaft and the collar and include flat ends supported by a frame of the tracked vehicle. The '807 patent also discloses a pair of bushings arranged on either side of the collar with the shaft and bushings disposed within a roller shell. One bushing is axially located between the central collar and a shoulder on the roller shell. The other bushing is axially located between the collar and a snap ring that fits into an annular groove in the roller shell. The '807 patent discloses an embodiment with only one bushing, where the other bushing is included as an integral part of the shell. The '807 patent discloses closure covers arranged on opposite ends of the shaft. Snap rings disposed in annular grooves at either end of the shaft retain the disclosed closure covers on the shaft. The '807 patent further discloses sealing devices arranged between the bushings and closure covers. In particular, the '807 patent discloses that O-rings disposed between the bushings and the roller shell help to prevent leakage of oil from the roller.
Although the roller disclosed in the '807 patent attempts to simplify the assembly and disassembly of the roller, the disclosed roller may still be less than optimal. In particular, the disclosed roller still relies on a plurality of snap rings to retain and axially locate the bushing and the closure covers on the shaft. The disclosed roller assembly also requires a plurality of O-rings to prevent leakage of oil from the roller. The use of numerous snap rings and/or O-rings increases the cost of manufacturing the roller by increasing the number of piece-parts and the number of steps required to assemble those parts. Additionally, during operation, frictional forces within the roller can generate heat, which can cause the lubricant to degrade faster and can also increase the rate of wear of the roller components. The amount of heat generated within the roller increases as the diameter of the sealing devices increases. Because the roller of the '807 patent uses a stepped shaft, the sealing devices of the '807 patent have relatively large diameters, resulting in an increased amount of heat generation, which in turn can decrease the operating life of the roller.
The roller assembly of the present disclosure solves one or more of the problems set forth above and/or other problems of the prior art.